http://qatestlab.com/ A software testing company distinguishes 3 patterns of handling software concurrency issues. They are: pessimistic pattern of concurrency control, optimistic pattern of concurrency control and pattern with no control of concurrency issues.

Checkout a session: (Click to enlarge) Checkout a session: The next step is to checkout a session. Access control rules determine which users are allowed to checkout a session to which accounts on which systems. Alternately, a user can request one-time access (authorized through a workflow process). In either case, concurrency limits may be in place, for example to ensure that no more than two administrators work on the same system at the same time.

Recommended by Dr. Dobbs and top rated on Amazon.com. The book approaches the topic from a design pattern point of view. It introduces and summarizes Java's concurrency support, shows readers how to initiate, control, and coordinate concurrent activities, and offers numerous recipe-like techniques for designing and implementing Java structures that solve common concurrent programming challenges.

http://qatestlab.com/ Many modern software products have to work simultaneously with many users accessing the same data. It is known that various patterns of solving application concurrency issues are used nowadays. Each of the patterns has its special features.